Go here to select one of your Pokémon and put them up for trade.
Other players will be able to request trades for your Pokémon. You can also list some requests. At the moment, you can list three requests, and maximum of 10 pokemons in each request. In that case, trade would be completed if other players can meet any one of your request(s).
Once you put your Pokémon to trade, you will not be able to use him in your game unless you call him back.
Your Trade Request
Go here to see if anybody has requested a trade with you or if any of your request have been accepted. You can also call back your Pokémon if you don't wish to trade it anymore.
Search Trade
Go here to search for trades that other players have posted.